1. Field of the Invention
This invention relates to a multiple system vehicle brake and especially relates to a fluid brake pressure control system which controls a hydraulic break pressure of a rear brake system in response to a deceleration of the vehicle.
2. Description of the Prior Art
It is well-known to control a wheel brake pressure in response to deceleration of the vehicle and to prevent wheel lock by excessive brake pressure supply, especially when the vehicle load is small. However, in conventional devices designed by such technique, the supply of a hydraulic brake pressure is not enough to accomplish a sufficient braking force for wheel locking when the vehicle load is large, because the above-mentioned devices were designed only for use with empty vehicles in which wheel locking can easily be controlled.
A device which is also well-known as an advancement in order to improve the above-mentioned device comprises having two different wheel brake control pressure between an empty vehicle and a fully loaded vehicle, with the latter pressure being set up with a slightly higher value than the former pressure as shown in FIG. 2, line Q-C. However, even this improvement was not found to be sufficient for establishing the ideal braking control pressure curve as shown in FIG. 2, line d.